The discovery of nucleosomes has added greatly to our understanding of the elementary organization of DNA in eukaryotic chromatin. Most of the studies on nucleosomes have been concentrated on their uniformity; however, the evidence that they are heterogeneous is very strong and there are indications that nucleosomes of active chromatin have an altered conformation. Very little is known of the packaging of nucleosomes to form the next higher order of chromatin structure. This proposal is addressed to the possible involvement of three groups of proteins in nucleosome heterogeneity and in higher order chromatin structure. The groups are: (1) subfractions of the histones making up the protein core of the nucleosome, H2A, H2B, H3 and H4, (2) subfractions of histone H1 which are outside the nucleosome and (3) subfractions of a group of non-histone chromatin proteins, the HMG's, which have been implicated as structural proteins. The first part of the study is aimed at determining if specific subfractions of these proteins are located in "active" and "inactive" chromatin as defined by susceptibility to DNase I and DNase II. The second part of the study is aimed at how these proteins might be involved in chromatin structure by using circular dichroism and fluorescence anisotropy to determine if protein-protein interactions occur between specific subfractions. Wheat chromosomal proteins have several properties which make wheat the organism of choice for these studies.